The present invention relates to a device for developing an exposed photosensitive material using a developing solution. More particularly, the invention relates to a developing device for photosensitive material appropriate for producing planographic printing plates.
In a conventional high-volume developing device for processing planographic printing plates, the photosensitive material is conveyed by a plurality of pairs of rollers. During such conveyance, a developing solution is applied to the exposed surface of the photosensitive material using a sprayer or the like to develop the photosensitive material. After the exposed (or unexposed, as the case may be) portion of the photosensitive layer of the photosensitive material is dissolved or swelled by the developing solution, that portion of the photosensitive material is rubbed off with a brush.
The efficiency of the developing process can be enhanced by heating the developing solution. In such a case, however, if the developing solution is alkaline, it has a tendency to absorb carbon dioxide from the ambient air at a high rate. This cause rapid fatigue of the developing solution due to a resulting drop in the degree of alkalinity of the solution as a result of a neutralizing reaction with the carbon dioxide.
In order to overcome this problem, a technique involving applying only the minimal amount of developing solution and rubbing off the dissolved portions of photosensitive material has been proposed, for example, in U.S. Pat. No. 4,222,656. Unfortunately though, it has been found that incomplete development and contamination in printing are likely to occur.